The present invention relates to a receiver and to a semiconductor integrated circuit having the receiver. More specifically, the present invention relates to a receiver that receives a signal, for instance, through an AC-coupling element, and to a semiconductor integrated circuit having such a receiver.
When wiring is used to directly transmit a signal between a plurality of semiconductor chips that differ in power supply voltage, semiconductor chip breakage or signal transmission failure may occur due to a voltage difference in DC voltage components of the signal to be transmitted. Therefore, when a signal is to be transmitted between the semiconductor chips that differ in power supply voltage, an AC-coupling element is coupled between the semiconductor chips so as to transmit only an AC signal. A capacitor or a transformer may be used as the AC-coupling element.
A certain method of signal transmission through an AC-coupling element indicates the direction of data transition in accordance with the amplitude direction of a pulse signal to be transmitted. When, for instance, a pulse signal having a positive amplitude is transmitted, the level of data is found to have transitioned from L to H (risen). When a pulse signal having a negative amplitude is transmitted, the level of data is found to have transitioned from H to L (fallen). This signal transmission method has the following problem although it can reduce a current consumption and a circuit area as compared to the other signal transmission methods.
A case where a transformer is used as the AC-coupling element is explained below. When transmitting a pulse signal having a positive amplitude, this signal transmission method causes a current to flow temporarily from one end of a primary coil to the other end. A positive electromotive force (a pulse signal having a positive amplitude) is then generated in a secondary coil in accordance with an electrical current change in the primary coil. On the other hand, when transmitting a pulse signal having a negative amplitude, this signal transmission method causes a current to flow temporarily from the other end of the primary coil to the one end. A negative electromotive force (a pulse signal having a negative amplitude) is then generated in the secondary coil in accordance with an electrical current change in the primary coil.
If the current flowing from the one end of the primary coil to the other end is blocked when the pulse signal having a positive amplitude is transmitted, a negative electromotive force (a counter pulse having a negative amplitude) is generated in the secondary coil in accordance with an electrical current change in the primary coil. Similarly, if the current flowing from the other end of the primary coil to the one end is blocked when the pulse signal having a negative amplitude is transmitted, a positive electromotive force (a counter pulse having a positive amplitude) is generated in the secondary coil in accordance with an electrical current change in the primary coil. Therefore, the receiver may acquire such a counter pulse as a normal pulse signal that indicates the direction of data transition. In other words, the receiver may erroneously determine the logic value of data.
A solution to the above problem is disclosed in “A 2.5 kV isolation 35 kV/us CMR 250 Mbps 0.13 mA/Mbps digital isolator in standard CMOS with an on-chip small transformer” (S. Kaeriyama, S. Uchida, M. Furumiya, M. Okada, M. Mizuno, 2010 Symposium on VLSI Circuits, Technical Digest of Technical Papers, 2010, pp. 197-198).
A configuration disclosed in “A 2.5 kV isolation 35 kV/us CMR 250 Mbps 0.13 mA/Mbps digital isolator in standard CMOS with an on-chip small transformer” (S. Kaeriyama, S. Uchida, M. Furumiya, M. Okada, M. Mizuno, 2010 Symposium on VLSI Circuits, Technical Digest of Technical Papers, 2010, pp. 197-198) compares the amplitude of a pulse signal having a positive amplitude to the amplitude of a pulse signal having a negative amplitude to determine which pulse signal is a normal pulse signal indicative of the direction of data transition. A related art disclosed in the above document uses such a configuration to prevent the logic value of data from being erroneously determined.
Other related arts are disclosed in Japanese Unexamined Patent Publications Nos. Hei 8 (1996)-236696 and 2011-142175.
An integrated circuit disclosed in Japanese Unexamined Patent Publication No. Hei 8 (1996)-236696 has a three-dimensional structure formulated by vertically stacking integrated circuit chips. This integrated circuit is configured so that coupling inductance M is used to provide induction-based signal transmission between one portion of a vertically integrated circuit in one chip layer Ln and another portion of a vertically integrated circuit in another chip layer Lnx.
A configuration disclosed in Japanese Unexamined Patent Publication No. 2011-142175 includes an AC-coupling element and a receiver. The AC-coupling element generates a reception signal V2 whose voltage changes in accordance with electrical current changes in an input transmission signal V1. The receiver reproduces the transmission signal V1 from the reception signal V2 by performing an integration operation on a numerical value based on the order of differentiation from the transmission signal V1 to the reception signal V2.